Acute angle closure crisis deserves its own special mention, as it
is one of the few true emergencies in the glaucoma world. Of all of the
forms of glaucoma, angle closure has a much greater chance to cause
permanent vision loss than open angle glaucoma, and the acute crisis
(frequently called an acute attack) probably accounts for a lot of this
damage. The mechanism by which it happens was described in the preceding
section (Why isn’t glaucoma either there or not there—what makes you an
angle closure suspect?)see section Why isn’t glaucoma either there or not there?. It happens to those with angle closure under the
situation where aqueous humor movement from behind to in front of the iris
is so blocked that the pressure behind the iris pushes it against the
meshwork and stops all aqueous outflow (Figure 7). Eye pressure can rise to numbers like 70
millimeters of mercury (compared to the normal 15). This is so high that
permanent damage to ganglion cells in the optic nerve happens in days to
weeks rather than the much longer, slower process of typical
glaucoma.

It is the sudden increase in pressure that causes the severe
symptoms of the attack. A link between the stomach and the eye causes an
attack to be not only the worst pain that people ever remember having, but
also it causes nausea and vomiting. Sometimes the stomach problem is so
prominent that people go to an emergency room and the staff pays attention
to that, thinking it is appendicitis, before realizing that the eye is the
cause. Acute attacks also get misdiagnosed as migraine headaches.

The eye symptoms of acute crisis are pain, poor vision in the
involved eye, redness of the white part, and a bigger and irregular pupil
shape. More than 90% of acute crises are in one eye only, but for one in
10 persons it happens in both eyes. In order to see if an eye problem is
in one eye or the other, one should cover one eye then cover
the other with a hand. In the excitement of being in pain, we often forget to do such
simple things.

One thing that sets off the crisis is having the pupil half-way dilated. This occurs with
stress, excitement, spending time in a dark place (such as a dimly lit
restaurant), or being exposed to medications that dilate the pupil.
This sometimes happens during general anesthesia, since a drug that
dilates the pupil (atropine) is given by anesthesiologists. If you have
bad eye pain after surgery under general anesthesia, have an exam by an
eye doctor immediately. Acute attacks can also be caused by the many pills
that are given that can dilate the pupil while helping you with things
like incontinence, sinus troubles, and upper respiratory colds. The Food
and Drug Administration doesn’t distinguish the various kinds of glaucoma
in its warnings on drugs about “glaucoma”, so if you are an angle closure
suspect who has not had iridotomy, call your eye doctor before taking any
of these drugs. Most of the time, you’ll hear that it’s fine to take them.
After you have iridotomy, you can take any of these drugs safely. The
final types of drugs that can cause acute crisis are those used in the eye
doctor’s office to dilate the pupil for examination of the inside of the
eye. We’ve seen this a number of times over the years, and patients who
have had dilating drops and have pain the night of the exam and especially
into the next morning should go right back immediately to be checked.
There are a group of medicines that can cause a very unusual form of acute
angle closure in people who otherwise weren’t at risk for it (they don’t
have small eyes or other risk factors for angle closure). One such drug is
topiramate, a headache pill which is also used in epilepsy. Another group
of drugs that can do this are some antibiotics and some anti-anxiety medications(see section Can the treatments be worse than the disease?).

If you think you are having an acute angle closure crisis, go to the
office of an ophthalmologist (a medical doctor who does surgery and laser
surgery) or to an emergency room that you are sure has an ophthalmologist
on call. Most metropolitan areas have an “eye
trauma” center designated where immediate, appropriate care would be
available. Don’t drive yourself there, get a ride or take a cab.

The immediate treatment for acute crisis will most often fix it in
the first hour. The pressure is lowered by either eyedrops or by letting a
small amount of aqueous out of the eye. This sounds gruesome, but you
won’t feel it and it immediately relieves the pain. Sometimes, in order to
begin the lowering of pressure, a laser is used to treat the outer part of
the iris to move it away from the meshwork to let aqueous out faster
(laser iridoplasty). The vast majority of crises are relieved as soon as a
hole is placed in the iris with a laser (Figure 17). The laser most often used is called a neodymium-YAG
laser. It can be focused inside the eye to make the iris hole, without making
any incision or hole in the eye wall (cornea). There is a slight feeling
that something is happening, but typically only eye drop anesthesia is
needed. Several deliveries of the laser may be needed to make a hole less than 1 millimeter in diameter. That’s all it takes to relieve most crises.
Occasionally, a second type of laser is used in very thick irises (called
a continuous wave laser or diode) to thin things down before penetrating
with the neodymium-YAG. High quality centers have both available to use.
The opening is usually small enough that others can’t see it from normal
social distances. Those who get within 6 inches of your face for long
enough to see the iris hole are people who know you well enough that
they’re concentrating on other things. Sometimes a small hole is made
initially and it is made bigger a month later.

The other eye should have a hole made, too, though most persons want
to wait a day or so to try to get back vision in the first eye. Putting it
off for a long time is a really bad idea.

If the crisis has been going on for longer than a day (and you may
not have been aware of it during that time) or if there have been
preceding little attacks in the past that led up to this one, the laser
iridotomy alone is not going to cure everything. There can be scars in the
angle that won’t go away, leading eye pressure to stay high. There may
already be damage to optic nerve structure and visual field function, so
that vision is never fully normal again. Haziness in the lens of the eye
(cataract) may be already present or develop quite quickly after iridotomy
due to the prior high pressure.

Some have suggested that removing the lens (cataract surgery) would
be a good treatment for acute crisis. Since the reason for the crisis is
severe blockage of fluid movement between the iris and lens, that is a
correct statement, but removing the lens and replacing it with an
artificial intraocular lens by surgery in the middle of an acute crisis is
very difficult. Only the most experienced cataract surgeons, working at a
center with extensive equipment to operate on the retina and vitreous
inside the eye should even attempt this. On occasion, the acute crisis is
not broken by laser iris hole and by medication—this then calls for forms
of glaucoma surgery (see section Operations for glaucoma).

An uncommon type of glaucoma happens in some eyes that seem to have
a typical acute crisis, but do not respond to standard laser iridotomy,
with pressure remaining high. The doctor will see some special clues that
this condition, called malignant glaucoma has happened. Malignant glaucoma
got its name because it was difficult to deal with; it has nothing to do
with cancer. It even happens sometimes in persons who are not at risk for
typical angle closure. The mechanism involves a collapse forward within
the eye of the gel called the vitreous that fills the back two thirds of
the eye cavity. The best explanation at present is that the process
starts, like typical angle closure, with choroidal expansion, and in these
folks the vitreous collapses forward due to pressure behind it. The
treatments start with laser iridotomy, but then additional types of eye
drops, oral and intravenous medication, and often surgery to make a
channel through the vitreous gel are needed to cure the problem.

Figure 18: Malignant glaucoma. Drawings to illustrate the process that causes malignant
glaucoma. starts with expansion of the choroid (shaded in grey, and
thicker than the choroid in the normal eye (Figure 1). The higher pressure causes aqueous to
leave the front of the eye, causing a pressure that is higher in the
back of the eye and lower in the front. Normal eyes can make the
pressures equal by having water pass through the vitreous gel that
fills the eye. Eyes with malignant glaucoma have poor water flow
through the vitreous and it collapses forward, carrying the lens and
iris with it until the angle is closed (lower drawing).

If you would like to support the cost of providing and maintaining this book with a charitable donation of any size,
please click here.